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Published on: August 17, 2016
Aluminum-26 in deep-sea sediment
Science (New York, N.Y.)
|September 17, 1976
Summary
Aluminum-26 (26Al) activity in North Pacific sediment aligns with atmospheric cosmic ray production, suggesting minimal cosmic dust contribution. This finding supports understanding cosmogenic nuclide sources.
Area of Science:
- Geochemistry
- Cosmochemistry
- Paleoceanography
Background:
- Cosmogenic radionuclides like Aluminum-26 (26Al) and Beryllium-10 (10Be) are produced by cosmic ray interactions in the atmosphere.
- Sedimentary records provide valuable archives for studying past environmental conditions and radionuclide deposition.
Purpose of the Study:
- To quantify the activity of Aluminum-26 (26Al) in a North Pacific sediment core.
- To determine the ratio of Aluminum-26 (26Al) to Beryllium-10 (10Be) in the sediment.
- To compare these ratios with atmospheric production rates and other environmental archives.
Main Methods:
- Radiometric analysis of sediment cores to measure Aluminum-26 (26Al) activity.
- Calculation of the Aluminum-26 (26Al)/(10)Be ratio in sediment and comparison with published data from ice cores and theoretical production values.
Main Results:
- The measured (26)Al activity in the North Pacific core was 0.081 +/- 0.046 dpm/kg.
- The (26)Al/(10)Be ratio in the sediment was 0.018 +/- 0.011 (0.019 +/- 0.012 corrected for decay).
- This ratio closely matches values found in Greenland ice (0.017 +/- 0.008) and calculated atmospheric production rates (0.013 +/- 0.006).
Conclusions:
- The (26)Al/(10)Be ratio in the North Pacific sediment is consistent with production by cosmic rays in the atmosphere.
- The contribution of extraterrestrial cosmic dust to the measured (26)Al is likely small.
- This study validates the use of cosmogenic radionuclides in marine sediments for reconstructing atmospheric processes.
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